Golden Scale

Allows you to dive for even longer. Beat the record you set as young Link at the fishing pond (if you didn't make a record, catch a record breaker now and then catch one that beats it). It also has to be bigger than 14 pounds. You'll either have to plant a magic bean next to the Lake Hylia Lab as young link, beat the Water Temple, or use the Scarecrow's Song and a hookshot in order to get to the fishing pond. Try finding the huge fish near the sticks sticking out of the water and under the log in the middle of the lake. Use your Iron Boots to look under water to help you find it.